What is the best treatment approach for a patient presenting with canker sores?

Treatment of Canker Sores

Start with betamethasone sodium phosphate 0.5 mg dissolved in 10 mL water as a rinse-and-spit solution, holding in the mouth for 2-3 minutes and using 1-4 times daily, which is the cornerstone first-line treatment recommended by dermatology guidelines. 1

First-Line Treatment Algorithm

Topical Corticosteroids (Primary Treatment)

• Betamethasone sodium phosphate 0.5 mg in 10 mL water is the gold standard: hold for 2-3 minutes, spit out, use 1-4 times daily 1, 2
• For localized ulcers on accessible areas, apply clobetasol 0.05% ointment mixed 50:50 with Orabase twice daily directly to dried mucosa 2, 3
• Alternative option: fluticasone propionate nasules diluted in 10 mL water twice daily 2

Pain Management (Use Concurrently)

• Benzydamine hydrochloride oral rinse or spray every 3 hours, especially before eating, for immediate pain relief 1, 3
• Barrier preparations like Gelclair mucoprotectant gel applied three times daily to form protective coating over ulcers 3
• For severe pain, viscous lidocaine 2% can be applied up to 3-4 times daily 3

Oral Hygiene Measures (Essential Adjunct)

• Warm saline mouthwashes daily to reduce bacterial colonization 1, 3
• 0.2% chlorhexidine digluconate mouthwash 10 mL twice daily for antiseptic effect—dilute by 50% if excessive stinging occurs 1

Second-Line Treatment for Non-Responders (After 1-2 Weeks)

• Tacrolimus 0.1% ointment applied twice daily for 4 weeks for refractory cases 1, 2, 3
• For severe localized ulcers: weekly intralesional triamcinolone (total dose 28 mg) combined with topical clobetasol 0.05% 1, 2

Systemic Therapy for Severe or Recurrent Disease

When to Escalate to Systemic Treatment

Use systemic therapy for highly symptomatic ulcers or frequent recurrences that don't respond to topical treatment.

• Prednisone/prednisolone 30-60 mg (or 1 mg/kg) daily for 1 week, then taper over the second week for acute severe episodes 1, 2
• Colchicine is particularly effective for recurrent aphthous stomatitis, especially when associated with Behçet disease 1, 2
• Azathioprine 2.5 mg/kg/day for severe cases with frequent recurrences requiring long-term control 1, 2

Critical Pitfalls to Avoid

• Never use corticosteroid rinses if active infection is present—treat candidiasis first or concurrently 1
• If candidal infection is suspected (white coating, burning), treat with nystatin oral suspension 100,000 units four times daily for 1 week or miconazole oral gel 5-10 mL held in mouth after food four times daily for 1 week 1, 3
• Dilute chlorhexidine by 50% if it causes excessive soreness 1
• For lip involvement, apply white soft paraffin ointment every 2 hours 3

Evidence Quality Note

The treatment hierarchy is based on consistent recommendations across multiple dermatology guidelines from 2025-2026, with topical corticosteroids universally recognized as first-line therapy. Research on low-level laser therapy shows promise 4, 5, but lacks the guideline-level endorsement of established topical corticosteroid protocols. The stepwise approach from topical to systemic therapy follows the WHO pain management ladder principle 2.